The present invention is directed to flush systems for toilets and urinals. It finds particular application in replacement assemblies for converting manual flush systems to automatic operation.
Operators of public facilities have found that the use of automatic flush systems for toilets and urinals provides advantages in one or more of the areas of sanitation, water conservation, and maintenance cost. For this reason, much new construction employs automatic flush systems. Many of the facilities in which automatic flush systems would be most advantageous, however, have already been built with manual flush systems, and the conversion to automatic operation can involve costs that makes the desirability of the conversion problematic.
FIG. 1 depicts the typical existing manual flush system employed in most American urinals and many other toilet installations. The flush system 10 includes a body section 12 and an upper housing 14. The upper housing is removably secured to the body by threads 15. The body 12 is connected between an inlet line 16, which receives water from the main supply, and an outlet line 18 through which water flows to flush the urinal. The upper housing 14 holds in place a cap or dome 20, which defines, with the inner surfaces of the body 12, a composite chamber 22 divided in two parts by a flexible diaphragm 24. The upper chamber 26 is a pilot chamber, while the lower chamber 28 is the main chamber with which the inlet line 16 communicates.
The diaphragm 24 includes an annular main flexible diaphragm plate 24a, to the interior of which is secured an elongated cylindrical guide member 24b by a collar 24c and a retaining ring 24d. The collar 24c both stiffens the diaphragm assembly 24 and acts as a guide by virtue of an annular guide-flange portion 24e extending upward from its upper surface. At the lower end of the lower cylindrical guide 24b are provided spacer fins 24f, which engage the main outlet passage wall 35 while permitting the flow between wall 35 and the cylindrical guide member 24b.
An outlet conduit 29 that communicates with the outlet line 18 forms an outlet-defining main valve seat 30 at its upper end. The diaphragm 24 ordinarily is seated on the main valve seat 30 and thereby prevents water from flowing directly from the main chamber to the outlet line 18. The seal between the diaphragm 24 and the main valve seat 30 is effected by the force of water pressure in the pilot chamber 26. The diaphragm 24 forms a pressure-equalizing orifice 32, which enables the steady-state pressure in the pilot chamber 26 to equal that which prevails in the main chamber 28 as a result of its communication with inlet line 16. Since the surface area over which the pilot-chamber pressure acts on the top surface of the diaphragm 24 is greater than that over which the main-chamber pressure operates on the lower diaphragm surface, a net downward force seals the diaphragm 24 against the main valve seat 30.
The flush system is operated to flush the urinal by relieving the pressure in the pilot chamber 26 so that the main-chamber pressure causes the diaphragm to flex and lift from the main valve seat 30 and thereby permit rapid water flow from the inlet line 16 through the main chamber 28 and the outlet defined by the valve seat 30, from which water flows through the outlet line 18 to flush the urinal or toilet. This pressure is relieved through a relief opening 36 in the diaphragm 24, which is ordinarily stopped by a pilot valve member 38 seated in a pilot seat 40 that the diaphragm 24 forms around the relief opening 36.
By operating a lever 42, the user drives a plunger 44 against a pilot valve rod 46, which displaces the pilot valve member 38 from the pilot seat 40, thereby relieving the pilot-chamber pressure. Consequently, the main-chamber-pressure force overcomes the pilot-chamber-pressure force and flexes the diaphragm to the open position depicted in FIG. 2.
The pilot valve member 38 then falls back into the pilot seat 40, either because the user has released lever 42 or because the pilot valve member 38, which is slidably mounted on the pilot valve rod 46, slides down on it. Then, after a short delay determined by the inlet water pressure and the flow resistance of the equalizing orifice 32, the pressure inside the pilot chamber reaches a level high enough that the net force on the diaphragm 24 is again downward, and the seal of the diaphragm 24 to the main valve seat 30 is re-established.
A conventional way to convert a toilet or urinal to automatic operation is to remove the entire existing flush-control system 10, including the body 12 and the upper housing 14 together with all of their contents, from the inlet and outlet lines 16 and 18. An automatic system is then connected in its place to lines 16 and 18 and possibly wired to building power.
Clearly, this approach has some drawbacks if a large number of flush systems are to be replaced, as is often the case in large public facilities. Not only is the cost of each new automatic flush system a significant factor, but so is the loss incurred if the old flush systems are simply discarded, as they ordinarily have to be.
An approach less wasteful of the existing installed base would be more desirable, but there are reasons why replacement of the entire flush system has heretofore been favored. Any reduction in the loss from discarding the part may well be outweighed by the cost of performing a complicated replacement operation that retains existing parts. Moreover, if parts are retained by simply employing an electromechanical operator to operate the pilot valve member 38, the resultant power usage requires an electrical connection, large batteries, or frequent battery replacement.
To avoid the latter problem, some replacement flush units have employed a different approach to pilot-chamber pressure relief. In this approach, pressure is not relieved through a relief opening in the diaphragm. It is relieved instead through a relief passage provided in the body 12 between the pilot chamber 26 and the outlet line 18. This approach can avoid high power consumption because the pilot valve member can control the pilot-passage flow with an operating-member stroke that is short in comparison with that necessitated in the conventional manual system by the movement of the diaphragm that forms the relief opening. Unfortunately, such an approach necessitates replacement of the entire flush unit.
Another approach is exemplified by the device described in U.S. Pat. No. 4,793,588 to Laverty. In the Laverty arrangement, a replacement includes a cylindrical passage-defining extension that extends into from cap 20 to the opening 36 in the diaphragm with the outer cylindrical surface in slidable, sealing relationship with the diaphragm's opening-defining surface. The cap also forms a recess in which a "valve body" is mounted that defines two passages, one of which provides fluid communication with the pilot chamber, the other of which provides fluid communication a passage in the cylindrical extension that in turn communicates with the outlet 18. A solenoid controls communication between the two valve-body passages, and, because the "valve body" is stationary, the solenoid travel does not have to be great. However, the cylindrical extension requires a resilient sealing member such as an O-ring that must permit the (typically rubber) diaphragm with which it forms a seal to slide, and this requirement is difficult to meet while consistently avoiding binding or cocking of the diaphragm.